i) Noise Margin: It is the amount by which signal exceeds the threshold for a proper 0 or 1.

Example: A circuit is designed to swing between 0.0V and 1.2 V. Below 0.2V is considered as 0 and anything above 1V is considered as 1 volt. Then noise margin for a '0' would be the amount that signal is below 0.2 volts and noise margin for '1' would be amount by which a signal exceeds 1 volt.

ii) Fan-in: The fan-in of a logic gate is the number of its inputs.

iii) Fan-out: The fan-out of a logic gate is the number of its output connections to other gates.